U.S. Pat. No. 4,375,021, in the name of Franco T. Pardini and Francesco DeVizzi, describes the use of a magnetic assembly arranged about the circuit breaker contacts for electrodynamically repulsing the contacts and for electrodynamic motivation of the arcs that occur when the contacts become separated. The arc chute used within the breaker for cooling and extinguishing the arc is formed by enfolding a metal strip partially around an insulating support substrate.
U.S. Pat. Nos. 2,005,684 and 2,551,822 both teach arc chute assemblies that contain a composite structure of one material having good arc resistant properties such as asbestos alongside another material having good physical support properties. Asbestos materials, having excellent high temperature and electrical resistance properties, however, are no longer available to the electrical industry by legislative mandate.
When the Pardini et al. circuit breaker is used to interrupt short circuit current at rated voltages in excess of 500 volts, it has been determined that the glass fibers in the arc chute side supports could negatively affect arc interruption due to the presence of alkaline metals such as sodium and calcium in the glass fibers. The low ionization potential of these metals contributes to the conductivity of the arc, which in turn, interferes with the rapid extinction of the arc at the higher voltages.
U.S. pat. application No. Ser. No. 056,187, filed June 1, 1987, entitled "Electric Circuit Breaker Arc Chute Composition" describes a three-layer laminate structure for arc plate side supports wherein the outer layers consist of a resin-impregnated cloth fiber while the inner support layer consists of a resin-impregnated glass fiber. The three-layer configuration ensures that the higher resistance cloth fibers face the circuit breaker contacts.
One purpose of the instant invention accordingly is to provide arc chute side support materials having the necessary thermal and electrical resistant properties while avoiding ionization of the glass components by means of an oriented and color-coded two-layer configuration which is less expensive to manufacture than the three-layer design.